University of Johannesburg

About: University of Johannesburg is a education organization based out in Johannesburg, South Africa. It is known for research contribution in the topics: Population & Context (language use). The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.

Test, Model, and Method Validation: The Role of Experimental Stone Artifact Replication in Hypothesis-driven Archaeology

Abstract: For many years, intuition and common sense often guided the transference of patterning ostensibly evident in experimental flintknapping results to interpretations of the archaeological record, with little emphasis placed on hypothesis testing, experimental variables, experimental design, or statistical analysis of data. Today, archaeologists routinely take steps to address these issues. We build on these modern efforts by reviewing several important uses of replication experiments: (1) as a means of testing a question, hypothesis, or assumption about certain parameters of stone-tool technology; (2) as a model, in which information from empirically documented situations is used to generate predictions; and (3) as a means of validating analytical methods. This review highlights the important strategic role that stone artifact replication experiments must continue to play in further developing a scientific approach to archaeology.

Au Nanocomposite Based Chemiresistive Ammonia Sensor for Health Monitoring

Abstract: We have developed a fast and highly sensitive chemiresistive sensor based on the nanocomposite of polysaccharide (guar gum) and gold nanoparticles for the room temperature detection of ammonia in the range of 0.1 parts-per-quadrillion (ppq) to 75 000 parts-per-million (ppm). Sensor response, selectivity, and stability studies reveal excellent sensing of the nanocomposite. The room temperature operation under ambient conditions and the wide range sensing indicates that the composites can be explored for environmental as well as biomedical applications. We have for the first time quantified the ammonia level released from the urine and blood serum of human beings using the resisitive sensor. The urine ammonia level was found to be ∼24 000 ppm and is higher for patients with renal problems. This demonstrated the utility of the sensor for health monitoring.

Global Diversity of Marine Isopods (Except Asellota and Crustacean Symbionts)

Abstract: The crustacean order Isopoda (excluding Asellota, crustacean symbionts and freshwater taxa) comprise 3154 described marine species in 379 genera in 37 families according to the WoRMS catalogue. The history of taxonomic discovery over the last two centuries is reviewed. Although a well defined order with the Peracarida, their relationship to other orders is not yet resolved but systematics of the major subordinal taxa is relatively well understood. Isopods range in size from less than 1 mm to Bathynomus giganteus at 365 mm long. They inhabit all marine habitats down to 7280 m depth but with few doubtful exceptions species have restricted biogeographic and bathymetric ranges. Four feeding categories are recognised as much on the basis of anecdotal evidence as hard data: detritus feeders and browsers, carnivores, parasites, and filter feeders. Notable among these are the Cymothooidea that range from predators and scavengers to external blood-sucking micropredators and parasites. Isopods brood 10–1600 eggs depending on individual species. Strong sexual dimorphism is characteristic of several families, notably in Gnathiidae where sessile males live with a harem of females while juvenile praniza stages are ectoparasites of fish. Protandry is known in Cymothoidae and protogyny in Anthuroidea. Some Paranthuridae are neotenous. About half of all coastal, shelf and upper bathyal species have been recorded in the MEOW temperate realms, 40% in tropical regions and the remainder in polar seas. The greatest concentration of temperate species is in Australasia; more have been recorded from temperate North Pacific than the North Atlantic. Of tropical regions, the Central Indo-Pacific is home to more species any other region. Isopods are decidedly asymmetrical latitudinally with 1.35 times as many species in temperate Southern Hemisphere than the temperate North Atlantic and northern Pacific, and almost four times as many Antarctic as Arctic species. More species are known from the bathyal and abyssal Antarctic than Arctic GOODS provinces, and more from the larger Pacific than Atlantic oceans. Two areas with many species known are the New Zealand-Kermadec and the Northern North Pacific provinces. Deep hard substrates such as found on seamounts and the slopes are underrepresented in samples. This, the documented numbers of undescribed species in recent collections and probable cryptic species suggest a large as yet undocumented fauna, potentially an order of magnitude greater than presently known.

Information Security Culture

Abstract: In every organisation an information security culture emerges from the way in which people behave towards information and the security thereof. The procedures that employees use in their daily work could represent the weakest link in the information security chain. It is therefore importanr to develop and improve information security culture through a structured model that addresses employees behaviour. This article will discuss the concept of information security culture and a assessment approach developed to implement and improve such a culture.